1. Field of the Invention
This invention relates to an infrared suppressor system for a gas turbine engine, and more specifically, to an infrared suppressor system which blocks the line of sight into the engine and which provides for mixing of cooling air with the hot exhaust gases of the engine.
2. Summary of the Prior Art
With recent advancements in weapons detection technology, there is growing recognition, in the field, of the importance of reducing the infrared signature associated with gas turbine engines powering military aircraft and land combat vehicles. Signature reductions reduce the possibility of detection and pursuit by enemy anti-aircraft forces including heat-seeking missiles. In the past, various apparatus have been utilized to suppress infrared radiation from gas turbine engines. Generally, these prior art devices admit to two categories: one in which a center plug is disposed in the exhaust flow and cooperates to block the line of sight to the hot turbine parts of the engine; and the other of which blocks line of sight by ejecting the hot gases from the suppressor at substantial angle from the axial center line of the engine.
Prior art suppressors of they type just mentioned have been numerous. Improved suppressors have been developed to provide size and weight advantages and minimize installation penalties.
An example of such improved suppressors is disclosed in U.S. Pat. No. 4,295,332, Steyer et al, which shows the use of splitters that perform a dual function of mixing hot and cool gas flows to reduce gas temperatures and also block line-of-sight infrared radiation. Since the conception of the suppressor disclosed in U.S. Pat. No. 4,295,332, further developments have made possible even more compact and higher performance suppressor construction arrangements.
An additional consideration is that infrared suppressors are only necessary when an aircraft is flown under combat conditions. It is undesirable to use infrared suppressors under non-combat conditions because of their associated performance penalties. Previous practice has been to remove an entire suppressor under certain operational conditions. Removing an entire suppressor can be difficult and time consuming.
It is, therefore, a primary object of the present invention to provide an improved infrared radiation suppressor system for a gas turbine engine in a construction arrangement that is compact yet allows acceptable levels of engine performance.
It is another object of the present invention to provide an infrared radiation suppressor which obstructs the line of sight of the hot turbine parts of the engine when this is desired but can be easily altered to improve engine performance when infrared suppression is unnecessary.
It is still another object of the present invention to provide an infrared suppressor which provides complete and thorough mixing of hot exhaust gases with cooler ambient air to effect a reduction in the signature of the exhaust plume in a compact arrangement with acceptable losses of engine performance, but can be easily altered to improve engine performance when infrared suppression is unnecessary.